Important Parts of a Rolex Watch: The Rolex Case
Welcome to the next chapter of our Important Parts of a Rolex Watch series where we’re studying each component of a Rolex in great detail. Following our in-depth look at the movements that power Rolex watches, we’re now turning our attention to the part that not only protects the movement but is arguably the most important design element of the watch: the Rolex case.
The History of the Rolex Oyster Case
In 1926, Rolex made history by inventing the world’s first waterproof watch case the company dubbed the Oyster. In fact, just one year later, the waterproofness of the Rolex Oyster was put to the test when it accompanied Mercedes Gleitze during her swim across the English Channel in 1927. After 10 hours in the water, the Rolex Oyster continued to perform perfectly!
Over the years, improving the water resistance of the Oyster case has continued to be a focus for Rolex. Today, all Oyster Perpetual watches (the broad label given most Rolex watches aside from Cellini watches) have a minimum water resistance of 100 meters. However, as expected, Rolex dive watches have much high water resistance ratings: Submariner 300 meters; Sea-Dweller 1,220 meters; Deepsea 3,900 meters.
Important Components of a Rolex Case
So, how does Rolex guarantee the water resistance of their Oyster cases? It’s all thanks to the case structure they patented back in 1926 that involves screwing down the bezel, winding crown, and caseback to the middle case.
A solid middle case: the center section of the Rolex Oyster case is stamped and machined from a solid block of metal (either steel, gold, or platinum depending on the model). This makes up backbone of the watch case to which all the other components are attached to.
Screw-down fluted caseback: The caseback of the Oyster case is solid, screwed-down, and fluted. This is to ensure that the case is hermetically sealed with no risk of water seeping into the movement. Rolex does not make transparent casebacks for any of their Oyster watches.
Crystal and bezel: The crystal that protects the dial is mounted on a gasket then the bezel is screwed down on top, ensuring an airtight seal. Previous crystals were made of acrylic while today’s crystals are all sapphire. Since 1953, most Rolex watches with a date function include a Cyclops magnification lens above the date except for discontinued versions of the Sea-Dweller and all versions of the Deepsea.
Screw-down winding crown: Rolex patented a waterproof winding crown in 1926, which was fitted with a metal gasket that would screw into a tube placed on the interior of the watch case. In 1953, Rolex debuted the Twinlock winding crown (fitted with two synthetic O-ring gaskets instead of one metal one) on the then-new Submariner to increase water resistance. In 1970, Rolex debuted the Triplock winding crown (with three O-ring gaskets) on the Sea-Dweller. Today, depending on the model, all Rolex Oyster cases are fitted with either a Twinlock or a Triplock winding crown.
Helium Escape Valve: In 1967, Rolex developed and patented the Helium Escape Valve to allow excess pressure built up in the watch to escape during post—saturation-diving decompression periods. The Sea-Dweller and Deepsea Rolex dive watches are fitted with helium escape valves.
Rolex Case Material Options
Rolex case material options include a variety of metals including stainless steel, gold, and 950 platinum. However, this being Rolex, there are some notable points to consider.
First of all, in 1985, Rolex was the first watchmaker to use 904L stainless steel (a superalloy that boasts anti-corrosion properties an offers exceptional sheen) for the cases of all its steel watches—moving away from the industry standard 316L stainless steel. As of 2018, Rolex began referring to the steel they use on their watches as Oystersteel.
Furthermore, Rolex currently produces all of its own 18k gold at an in-house foundry to ensure exceptional quality control. Plus, in 2005, Rolex developed and patented a rose gold alloy they call Everose, which promises to never fade.
Other Rolex terms to keep in mind when referring to case materials include Rolesor, (the combination of gold and steel on the same watch) and Rolesium (the combination of platinum and steel on the same watch).
Rolex Case Size Quick Guide
Over the course of Rolex’s history, the company has offered a wide variety of case sizes—even within the same watch collection. Here’s a quick Rolex case size guide.
Rolex Oyster Perpetual Case Sizes
|Oyster Perpetual||1931 – Present||34 mm|
|Oyster Perpetual||1959 – Present||36 mm|
|Ladies’ Oyster Perpetual||1964 – 2000s||24/25 mm|
|Midsize Oyster Perpetual||1960s – Present||31 mm|
|Oyster Perpetual 26||2014 – Present||26 mm|
|Oyster Perpetual 39||2015 – Present||39 mm|
Rolex Air-King Case Sizes
|Air-King||1945 – 2016||34 mm|
|Air-King Date||1958 – 1980s||35 mm|
|Air-King||2016 – Present||40 mm|
Rolex Datejust Case Sizes
|Men’s Datejust 36||1945 – Present||36 mm|
|Men’s Datejust Oysterquartz||1977 – 2000s||36 mm|
|Men’s Datejust II||2009 – 2016||41 mm|
|Men’s Datejust 41||2016 – Present||41 mm|
|Midsize Datejust||1960s – Present||31 mm|
|Lady-Datejust 26||1957 – 2015||26 mm|
|Lady-Datejust 28||2015 – Present||28 mm|
Rolex Date Case Sizes
|Men’s Date||1950s – Present||34 mm|
|Midsize Date||1960s – 1980s||31 mm|
|Ladies’ Date||1960s – 2000s||26 mm|
Rolex Explorer Case Sizes
|Explorer||1953 – 2010||36 mm|
|Explorer 39||2010 – Present||39 mm|
Rolex Submariner Case Sizes
|Submariner||1953 – 1959||38 mm|
|Submariner||1959 – Present||40 mm|
|Submariner Date||1966 – Present||40 mm|
Rolex GMT-Master / GMT-Master II Case Sizes
|GMT-Master||1955 – 1959||38 mm|
|GMT-Master||1959 – 1999||40 mm|
|GMT-Master II||1983 – Present||40 mm|
Rolex Day-Date “President” Case Sizes
|Day-Date 36||1945 – Present||36 mm|
|Day-Date Oysterquartz||1977 – 2000s||36 mm|
|Day-Date Masterpiece||2000 – 2015||39 mm|
|Day-Date II||2009 – 2016||41 mm|
|Day-Date 40||2016 – Present||40 mm|
Rolex Milgauss Case Sizes
|Milgauss||1956 – 1988||38 mm|
|Milgauss||2007 – Present||40 mm|
Rolex Daytona Case Sizes
|Daytona (Manual-Wound)||1963 – 1988||38 mm|
|Daytona (Automatic)||1988 – Present||40 mm|
Rolex Sea-Dweller Case Sizes
|Sea-Dweller||1967 – 2009||40 mm|
|Sea-Dweller Deepsea||2008 – Present||44 mm|
|Sea-Dweller||2014 – 2017||40 mm|
|Sea-Dweller||2017 – Present||43 mm|
Rolex Explorer II Case Sizes
|Explorer II||1971 – 1985||39 mm|
|Explorer II||1985 – 2011||40 mm|
|Explorer II||2011 – Present||42 mm|
Rolex Pearlmaster Case Sizes
|Pearlmaster||1992 – 2015||29 mm|
|Pearlmaster 34||2000 – Present||34 mm|
|Pearlmaster 39||2015 – Present||39 mm|
Rolex Yacht-Master Case Sizes
|Yacht-Master 40||1992 – Present||40 mm|
|Midsize Yacht-Master||1994 – 2016||35 mm|
|Ladies’ Yacht-Master||1994 – 2012||29 mm|
|Yacht-Master 37||2016 – Present||37 mm|
Rolex Yacht-Master II Case Sizes
|Yacht-Master II||2007 – Present||44 mm|
Rolex Sky-Dweller Case Sizes
|Sky-Dweller||2012 – Present||42 mm|